Resistance massecuite heater



Dec. 1968 F. B. PRICE ETAL 3,414,435

RESISTANCE MASSECUITE HEATER Filed Sept. 16, 1966 2 Sheets-Sheet 1 FIG.I i

INVENTORS'.

FRANK B. PRICE, RICHARD J. MORRONI, 4| NED L. LUCAS,

L 37 BY 52%? Dec. 3, 1968 F. B. PRICE ETAL 3,414,436

RESISTANCE MASSECUITE HEATER Filed Sept. 16, 1966 2 Sheets-Sheet 2 ATTORNEYS.

United States Pateut O 3,414,436 RESISTANCE MASSECUITE HEATER Frank B. Price, Edgewater, Richard J. Morroni, Denver, and Ned L. Lucas, Wheatridge, Colo., assignors to American Factors Associates, Limited, Honolulu, Hawaii, a corporation of Delaware Filed Sept. 16, 1966, Ser. No. 579,875 14 Claims. (Cl. 127-19) ABSTRACT OF THE DISCLOSURE Method and apparatus for heating substantial volumes of viscid materials such as massecuite and the like including inner and outer electrodes forming annular elongated restricted treatment passage of increasing dimensional area from inlet to outlet for confining flow of massecuite. Outer electrode having transition means and inner electrode having tapered end walls terminating in apex at each end forming inlets and outlets to treatment passage which are substantially coaxial with said passage for directing continuous massecuite flow into and from treatment passage. Upstream and downstream beams of insulator material for supporting inner electrode within outer electrode and insulating between same. Electric voltage impressed across electrodes for producing current flow in massecuite transversely of its direction of flow in treatment passage establishing a current density in massecuite on the order of .01 ampere per square centimeter.

This invention relates to the treatment of massecuite and similar materials and more particularly to a method and means for conditioning a stream of massecuite and similar materials by using electric resistance heating.

In the production of sugar the viscosity of the massecuite subsequent to crystal formation is not entirely suitable for crystal extraction in centrifugals. For the conditioning of massecuite to a suitable viscosity for feeding to a centrifugal separator various ways have been heretofore employed such as diluting and reheating to increase the viscosity of the massecuite without materially affecting the crystal formation.

Reheating of the massecuite has heretofore been accomplished by various means such as the circulation of hot water in pipes through a body of massecuite and also types of resistance heating have been employed. Accordingly, it is an object of the invention to provide a novel method and means for conditioning massecuite and similar materials for crystal extraction by electric resistance heating.

Another object of this invention is to provide a novel means for increasing the fluidity of massecuite which is simple, durable and eflicient in rapidly and uniformly heating large volumes of massecuite to a viscosity suitable for extraction treatment in a continuous centrifugal separator.

Yet another object of this invention is to provide method and apparatus for the heating of large volumes of the massecuite and similar materials in a continuous flow to substantial temperature increases in which the residence time is relatively short and the heating is uniform throughout the extent of the treatment zone.

A further object of this invention is to provide for the conditioning of massecuite by electric resistance heating at low current densities to prevent caramelization in the flow of massecuite passing from a crystallizer stage to a continuous centrifugal stage for separation of sugar crystals from associated mother liquor.

Other objects, advantages and capabilities of the invention will become apparent as the description proceeds with reference to the accompanying drawings in which:

FIG. 1 is a vertical section through an electric heater embodying novel features of this invention;

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FIG. 2 is a top plan view of the electric heater shown in FIG. 1 illustrating the upper transition member and drawn to a reduced scale;

FIG. 3 is a side elevation view of the electric heater assembly shown in FIG. 1 drawn to a reduced scale;

FIG. 4 is a top plan view of the inner electrode shown in FIG. 1 drawn to a reduced scale;

FIG. 5 is a bottom plan view of the inner electrode shown in FIG. 1 drawn to a reduced scale;

FIG. 6 is a sectional view taken along lines 66 of FIG. 1 showing the shaping of the intermediate portion of the upstream support beam and the interior of the casing for the inner electrode through which the beam extends;

FIG. 7 is a sectional view taken along line 7-7 of FIG. 1 showing the shaping of an end portion of the upstream support beam, the support of this beam in the end cap attached to the outer shell and the lead line passing through the beam;

FIG. 8 is a sectional view taken along line 88 of FIG. 1 showing the shaping of the end portion of the upstream support beam and the electric insulation on the adjoining side wall; and

FIG. 9 is a schematic circuit diagram showing the electric heater embodying the present invention in a sugarmaking process circuit.

Referring now to FIG. 1, the electric heater assembly 10 illustrated therein in general comprises an outer electrode 11 and an inner electrode 12 supported within the outer electrode to define a confined treatment passage 13 through which the flowing material being heated is passed by gravity flow. The electric power source 15, preferably an AC. source, is applied across the outer and inner electrodes 11 and 12 through electric lead lines 16 and 17 connected thereto to cause current to flow in the stream of material being heated by use of the electric conductivity of this stream of material to heat the material in a manner described more fully hereinafter.

The electric power source 15 is preferably variable and is illustrated as a variable trans-former having its primary winding connected to an external supply at L1 and L2 and its secondary winding connected across lead lines 16 and 17. The voltage may be manually regulated by a suitable control 14 connected thereto as is schematically illustrated to change the voltage applied to the electrodes and thus regulate the current density in the flowing massecuite. The electrode voltage can be automatically varied in response to measured temperatures of the heater such as a temperature sensing bulb 18 disposed at the discharge end of the outer electrode suitably coupled to control 14.

It has been found that, by regulating the electrode voltage and providing a passage 13 between the electrodes of increasing dimension from inlet to outlet as hereinafter described more fully, that current densities may be maintained at about and preferably below .01 ampere per square centimeter throughout the treatment zone which provides successful heating without caramelization.

The outer electrode 11 comprises a hollow shell 19 which may be of various shapes and is herein illustrated as box-like in section having smooth inner wall surfaces. This shell has apertured flanged portions 21 and 22 at its upstream and downstream ends, respectively. The upstream flanged portion 21 supports an upstream transition member 23 and the lower flanged portion 22 supports a downstream transition member 24 which are substantially identical in shaping and conduct material into and away from the shell 19.

The upstream transition member 23 includes side wall portions 27 which diverge from an upstream intake opening 28 at the top of the assembly to a downstream discharge opening 29 and terminates at the downstream end in an apertured flanged portion 31 which abuts the flanged portion 21 of the shell and is detachably secured thereto by a plurality of fasteners 32. The upstream end of the transition member 23 has an apertured flanged portion 33 for securing to suitable flow conducting lines which preferably pass from thecrystallizer stage as will be described hereinafter with respect to FIG. 9.

The lower transition member 24 includes side wall portions 35 which converge from an upstream intake opening 36 to a downstream discharge outlet 37 and terminates at its upstream end in an apertured flanged portion 38 which fits against the flanged portion 22 of the shell and is detachably secured thereto by a plurality of fasteners 39. The downstream end of the downstream transition member 24 terminates in an apertured flanged portion 41 for securing to suitable flow conducting lines which pass the stream of heated material from the heater to the continuous centrifugal separator as will be described more fully hereinafter with respect to FIG. 9.

The inner electrode 12 comprises a generally hollow body inclusive of side wall portions 44 which form a body which is generally box-like in section, an upstream closure portion 45 which comprises portions 45a which taper inwardly or diverge from the upstream end of the respective side wall portions 44 to an upstream apex 45b and a downstream closure portion 46 which comprises surface portions 46a which taper inwardly or converge at a downstream apex 46b. These side wall and upstream and downstream closure portions 44 and 45 and 46 of the inner electrode are joined in a sealed relationship at respective ends to define an interior sealed space or void 48. These wall enclosure portions are relatively thin, which provides for a lightweight body, and are of a material which has good heat and electric conductive characteristics.

The side wall portions 44 converge or taper inwardly from their upstream end to their downstream end and have smooth exterior surfaces. These smooth exterior surfaces of the side wall portions 44 and the inner side wall surfaces of the adjoining shell 19 define the treatment passage 13 which is circumferentially continuous and has a uniform dimension or spacing at the same point along the passage and in addition define a passage of increasing dimension along the passage from its inlet to outlet. The rate of increasing of the spacing or width of the passage 13 from its inlet to the outlet is selected to maintain constant the total resistance (the product of resistance times length) between the electrodes of the flowing material being treated, and thus a constant current density assuming the voltage across the electrodes remains constant.

While the hollow shell 19 of the outer electrode has been illustrated as of generally uniform dimension throughout its lengthwise extent with the side wall portion 44 of the inner electrode diverging throughout its lengthwise extent, a reversal of such relationship of these members may be utilized to define a passage of increasing dimension along the passage from its inlet to outlet. Specifically, the side wall portion 44 may be vertical throughout its length with its hollow shell 19 inclined outwardly to the vertical from intake to discharge..

The adjoining exterior surfaces of the upstream closure portion 45 and the inner wall surfaces 27 define an intake passage 51 which conducts the incoming material in a spreading pattern from intake opening 28 to the inlet of the Zone 13. The adjoining surfaces of the downstream closure portion 46 and the side wall portion 35 define an outlet passage 52 above the discharge outlet 37 which conducts the heated material in a converging pattern from the discharge outlet of the treatment passage 13 to and through discharge outlet 37.

The inner electrode 12 is supported within and in spaced relation from outer electrode 11 and is electrically insulated therefrom by means of upstream and downstream support beams 56 and 57 which extend through upstream and downstream casings 53 and 54 formed in parallel spaced relationship in the inner electrode body. The upstream and downstream casings 53 and 54 enclose the respective support beams and are secured to the side wall portions 44 to maintain the interior space 48 sealed.

The upstream support beam 56 includes a notched portion 56a on its upstream edge intermediate its ends and the downstream support beam 57 includes a notched portion 57a on its downstream edge intermediate its ends which fit into the upstream edge of the upstream casing 53 and the downstream edge of the downstream casing 54. These notched portions assist in the location of the support beams in the inner electrode so as to center the inner electrode within the outer electrode.

The support beams 56 and 57 extend beyond the respective encompassing casings 53 and 54 through the treatment passage 13 and through the opposing walls of shell 19 and are secured to shell 19 by identical upstream and downstream cap members 58 and 59 which encompass the ends of respective support beams and are detachably secured to the walls of shell 19 by suitable fasteners 61 and 62, respectively.

On the inner surface of shell 19 where the end of each support beam extends through the shell there is provided a layer of insulation 63 preferably generally circular in shape and oppositely of this layer on the outer surface of the inner electrode side wall portion there is disposed a corresponding layer of insulation 64 preferably of generally circular shape to further insulate the inner and outer electrodes at the point where they are joined by the support beams.

The upstream support beam 56 includes tapering or beveled surface portions 56b at each end on its upstream edge and the downstream support beam 57 includes tapering surfaces 57b (FIG. 8) at each end on its upstream edge. These beveled edges 56b and 57b extend along the upstream edges of the respective support members from the respective notched portions through passage 13 to its end and are knife-like in character so as to scour clean and eliminate stagnant buildup which would otherwise overheat and caramelize and eventually become a conductive carbonaceous deposit.

These support beams are of a suitable mechanically durable insulation material having good electric and heat insulating characteristics. An example of such insulation is a combination of linen impregnated and phenolic resin material manufactured by Ryerson and Sons under the brand name Ryertex.

Electric lead line 17 is connected at one end to the live side of power source 15 and at the other end is electrically connected at a terminal connection 65 to the inner electrode at a surface of casing 53. Lead line 17 extends through a packing gland 66 secured on one of the upper end caps 58 and a grooved or slotted portion 67 of the upstream beam which electrically insulate the lead line 17 from the outer electrode. Lead line 16 which is the ground lead is fastened at a connection 68 to the outer shell wall and at the opposite end is connected to the ground side of the A.C. source 15.

The method of increasing the fluidity or viscosity of flowing material such as massecuite will now be described with reference to a portion of the sugar refining process shown in FIG. 9 which includes a low raw vacuum pan 71 feeding a crystallizer stage 72 through a conducting line 73. The output of the crystallizer stage feeds a continuous stream of flowing massecuite material which has been cooled and crystallized through conductive lines 74 to a plurality of parallel arranged electric heaters 10 as above described with reference to FIGS. 18 in which the massecuite is heated to increase its fluidity and then passed in a continuous stream through valved conductive lines 75 in controlled quantities to continuous centrifugal separators 79 from which molasses passes through line 76 and raw sugar from line 77 from each centrifugal separator.

In the electric heater 10 the continuous feed of massecuite is conducted through an intake passage 51 into the treatment passage 13 through which the massecuite passes in a substantially linear flow path between adjoining inner and outer electrode surfaces. The primary heating is carried out in this treatment passage 13. The voltage applied across the inner and outer electrodes passes an electric current through the massecuite flowing in passage 13 which progressively heats this flowing material as it passes therethrough. Passage 13 as defined by the inner and outer electrode surfaces increases in width or sectional dimension in proportion to the increase in conductivity of the flowing material so that the total resistance of the massecuite between the electrodes along its flow path is constant so as to provide a substantially uniform heating in the passage 13.

The heated massecuite is then conducted through passage 52 and discharged through outlet 37 and is then directed into the continuous centrifugal separator 79 through line 75.

Apparatus embodying the present invention as illustrated and described hereinabove was tested and treated on the order of 100 cu. ft. of massecuite per hour using a power in the neighborhood of 33 kilowatts and 440 volts A.C. The residence time within the heater was about 100 seconds during which time the massecuite was raised in temperature about 25 F. The temperature of the massecuite at the outlet was normally maintained at about 125 F. to 130 F.

Other changes and modifications may be availed of within the spirit and scope of the invention as set forth in the hereunto appended claims.

We claim:

1 An electric heater for flowing massecuite and similar materials comprising an outer electrode inclusive of a hollow shell having an upstream intake end and a downstream discharge end for the intake and discharge of a flowing stream of massecuite being heated, an inner elec trode formed as a hollow sealed body supported within and electrically insulated from said outer electrode in spaced relation thereto, said electrodes defining an annular restricted treatment passage through which the massecuite is passed, said outer and inner electrodes having opposing side wall portions which progressively increase in spaced relationship along the treatment passage from the inlet to the discharge end, said intake end and discharge end of the shell being substantially coaxial with said treatment passage, said inner electrode having a tapered end wall portion terminating in an apex adjacent the intake end of the outer shell to direct the massecuite flow from said intake end to said treatment passage and a tapered end wall portion terminating in an apex adjacent the discharge end of the hollow shell to direct the massecuite flow from the treatment passage through the discharge end of the shell, and means for applying electrical potential across the inner and outer electrodes so that the entering massecuite is progressively heated when the current is caused to flow in the massecuite transversely of the direction of massecuite flow by the electrical potential across the electrodes while the massecuite progressively passes through said passage and out said discharge end.

2. An electric heater as set forth in claim 1 wherein said inner and outer electrodes are essentially box-like in section.

3. An electric heater as set forth in claim 1 wherein said electrical potential is variable and includes means responsive to the temperature of the massecuite in the passage to vary the potential to change the amount of heating of said flowing massecuite in said treatment passage.

4. An electric heater as set forth in claim 1 inclusive of an intake transition means for delivering flowing massecuite to the upstream intake end of said outer electrode shell and a discharge transition means for delivering heated flowing massecuite from the discharge end of said outer electrode shell, said intake transition means including tapering wall portions which diverge from an upstream inlet opening coaxial with the passage to a downstream discharge opening of substantially greater width than its inlet opening and said discharge transition means including tapering wall portions which converge from an upstream inlet opening to a downstream discharge opening coaxial with the passage of substantially lesser width than its inlet opening.

5. An electric heater as set forth in claim 1 wherein one of said electrodes includes substantially vertically extending side portions and the other of said electrodes includes side portions which incline to the vertical to provide a passage of increasing dimension from the inlet to the discharge end.

6. An electric heater as set forth in claim 1 wherein said electrodes and electrical potential are proportioned to establish a current density in the flowing massecuite on the order of .01 ampere per square centimeter.

7. An electric heater for flowing massecuite comprising an outer electrode formed of a hollow shell including annular side wall portions, an inner electrode formed of a hollow body including annular side wall portions, means for supporting said inner electrode within the outer electrode in spaced relation thereto to define a smooth substantially uninterrupted elongated annular passage between said side wall portions through which massecuite passes between an upstream annular inlet opening at one of its ends and a downstream discharge end at its opposite end, the spacing between said electrodes increasing in width progressively in the direction of the movement of said massecuite, said supporting means including an upstream beam and a downstream beam which extend through upstream and downstream portions to the inner electrode and are detachably secured at each end to the outer electrode, each said beam being of an electric insulating material for insulating between said inner and outer electrodes, means for applying an electrical potential across said electrodes to pass electric current through said massecuite transversely of its progressive movement in the passage, conductive means arranged substantially coaxial with said inlet opening for delivering flowing massecuite to the passage and having means for its attachment to a source of continuous feed of massecuite, and second conductive means arranged substantially coaxial with said discharge end for delivering the massecuite outflow from the passage and having means for its connection to an outflow conduit subject to continuous discharge.

8. An electric heater as set forth in claim 7 wherein said electric potential means includes an electric lead line extending through a portion of said outer electrode and through a portion of one of said support beams and electrically connects a live terminal of an electric A.C. power source to said inner electrode.

9. An electric heater as set forth in claim 7 wherein said support beams are provided with notched portions for engaging adjoining surfaces of the inner electrode for locating the inner electrode within the outer electrode.

10. An electric heater as set forth in claim 7 wherein adjoining portions of said inner and outer electrodes through which said beams extend include at least one layer of electric insulation.

11. An electric heater as set forth in claim 7 wherein each said beam includes upstream knife-like edge portions in said passage to reduce material buildup thereon.

12. The method of preparing massecuite and similar materials for crystal extraction which comprises moving massecuite to a heating chamber subject to a continuous feed and discharge of massecuite, confining the flow of the massecuite in said heating chamber between spaced inner and outer electrode side wall surface portions which define an annular shaped elongated restricted treatment passage through which the entering massecuite passes by gravity flow, directing the massecuite flow into and from said treatment passage through inlets and outlets arranged substantially coaxial with the annular inlets and outlets of said treatment passage, passing an electric current transversely of said massecuite flow in said passage, establishing a pre-selected and substantially uniform current density in said massecuite during substantially all of its progressive gravitational flow through said passage, and discharging the heated massecuite as feed to a continuous centrifugal separator.

13. The method as set forth in claim 12 wherin the retention time in the heating chamber is about 100 seconds and the temperature rise from inlet to discharge of the massecuite is about 25 F.

8 14. The method as set forth in claim 12 wherein the current density in the flowing massecuite is maintained on the order of .01 ampere per square centimeter.

References Cited UNITED STATES PATENTS 3/1915 Nash 219291 6/1953 Hoyt 127-19 XR ROBERT K. SCHAEFER, Primary Examiner. M. GINSBURG, Assistant Examiner. 

